System and method for multi-pair configuration over existing cabling infrastructure

ABSTRACT

A system and method for multi-pair configuration over existing cabling infrastructure. In one embodiment, a network device is configured through a selective activation of one or more physical layer devices that are coupled to a respective one or more of the conductor pairs that are identified in a diagnostic process. Aggregation can be performed on the data streams carried over the activated conductor pairs.

This application claims priority to provisional application No.61/650,685, filed May 23, 2012, which is incorporated herein byreference in its entirety.

BACKGROUND

1. Field of the Invention

The present invention relates generally to networking and, moreparticularly, to a system and method for multi-pair configuration overexisting cabling infrastructure.

2. Introduction

Ethernet devices continue to evolve in capability as the incrementalincreases in the standardized transmission rates have progressed byorders of magnitude. In a relatively short period of time, transmissionrates for standardized Ethernet devices have progressed from 10 Mbit/sto 100 Mbit/s, from 100 Mbit/s to 1 Gbit/s, from 1 Gbit/s to 10 Gbit/s,etc. Efforts are ongoing to identify the next transmission rate that isto be adopted as the next standard of Ethernet performance.

The significant advances in the standardized transmission rates hasprovided substantial benefits in increasing the available bandwidth inan Ethernet network. These large increases in available bandwidth haveenabled significant changes in the applications that can be supportedacross various types of networks. As the cost of bandwidth hasdecreased, so also have the performance barriers that have hinderedcertain types of applications.

Notwithstanding the substantial benefits that have been realized by thelarge increases in data transmission rates, those same large increasesin data transmission rates can likewise create other cost barriers thatcan hinder the deployment of some applications. Balancing the benefit ofthe increased data transmission rate are the implementation costs suchas system complexity, physical plant improvements (e.g., cabling),increased power consumed, etc. These implementation costs may bejustified in those instances where the full benefits of the increaseddata transmission rate are being realized. Where the full benefits ofthe increased transmission rate are not being realized, however, theimplementation costs can dominate and other potential solutions areneeded.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to describe the manner in which the above-recited and otheradvantages and features of the invention can be obtained, a moreparticular description of the invention briefly described above will berendered by reference to specific embodiments thereof which areillustrated in the appended drawings. Understanding that these drawingsdepict only typical embodiments of the invention and are not thereforeto be considered limiting of its scope, the invention will be describedand explained with additional specificity and detail through the use ofthe accompanying drawings in which:

FIG. 1 illustrates an embodiment of a mechanism that can leverage anexisting cabling infrastructure.

FIG. 2 illustrates an example of a cable diagnostic module in a physicallayer device module.

FIG. 3 illustrates a flowchart of a process of the present invention.

FIGS. 4A and 4B illustrates various embodiments of an aggregation layerin a network device.

FIG. 5 illustrates an embodiment of an energy efficiency control policyin a network device.

DETAILED DESCRIPTION

Various embodiments of the invention are discussed in detail below.While specific implementations are discussed, it should be understoodthat this is done for illustration purposes only. A person skilled inthe relevant art will recognize that other components and configurationsmay be used without parting from the spirit and scope of the invention.

The advances in standardized Ethernet communication have facedsignificant limitations in its adoption. A first limitation tonext-generation adoption is the implementation costs incurred in thedeployment of new cabling, connectors and magnetics to supportnext-generation data transmission rates. Where the location of such anext-generation system deployment is in an existing building, the costsof replacing the cabling infrastructure can prove daunting in thetransition from previous-generation data transmission rates.

A second limitation to next-generation adoption is the increased energycosts that would be incurred in supporting the next-generation datatransmission rates. Energy efficiency is a key consideration in Ethernetdevices as energy costs continue to escalate in a trend that hasaccelerated in recent years. For that reason, the IT infrastructure hasdrawn increasing scrutiny as a potential area where energy costs can bereduced. In light of current industry trends, the energy efficiencyissues presented by the deployment of next-generation data transmissionrates to support data bandwidth needs that are marginally aboveprevious-generation data transmission rates can cause significant energyefficiency concerns.

In the present invention, the implementation costs incurred throughnext-generation system adoption can be reduced through a solution thatobviates the need to deploy transmission equipment that takes a largeleap forward to the next standardized data transmission rate level. Asdescribed in greater detail below, a mechanism for multi-pairconfiguration over existing cabling infrastructure is provided thatlargely removes the burdens imposed by the deployment of the nextgeneration of standardized devices.

In one embodiment, the multi-pair configuration mechanism leverages theexisting cabling infrastructure through an initial identification of thecommunication channel characteristics of the network link. Thisidentification can be performed through cable diagnostics that aredesigned to determine the number of conductor pairs, the length of thenetwork cable, and the type of network cabling (e.g., Category 3, 5e, 6,6A, 7, 7A, 8, 8A, etc. Ethernet cabling). Next, a capability exchange isperformed between the link partners. In one embodiment, such acapability exchange can be performed using an auto-negotiation processbetween the link partners that can be extended using next pagemessaging. After the channel characteristics and the link partnercapabilities have been identified, a data transmission rate is selectedbased on the communication channel characteristics and the capabilitiesof the link partners. In one embodiment, a selection of a particularsignaling mechanism to be used can also be performed. Next, the networkdevice is configured through a selective activation of one or morephysical layer devices that are coupled to a respective one or more ofthe conductor pairs that are identified in the diagnostic process.Aggregation can be performed on the data streams carried over theactivated conductor pairs.

In one embodiment, the aggregation occurs below the media access controllayer. In another embodiment, the aggregation occurs above the mediaaccess control layer. The aggregation of the data streams carried overthe activated conductor pairs is designed to present an aggregated datastream for use by the network device. In one example, such an aggregateddata stream can be a greater than a one gigabit/s data stream. In thisexample, the greater than one gigabit/s data stream over an existingcabling infrastructure can provide a significant cost/benefitimprovement as compared to a ten gigabit/s data stream over anewly-deployed cabling infrastructure. In another embodiment, the linkis configured to start with a minimum number of conductor pairs and oncethe link is up, a capability exchange can be performed (e.g., using LinkLayer Discovery Protocol (LLDP)).

Replacing existing cabling infrastructures presents significant costchallenges. For example, the costs to rewire an existing Category 3, 5,or 5e cabling infrastructure in existing buildings may be substantial. Afailure to modernize such a cabling infrastructure could prevent theapplication of new technology. For example, next-generation 802.11acwireless access points can support wireless links having greater thanone gigabit/s data transmission speeds.

In the present invention, it is recognized that a new mechanism isneeded to leverage an existing cabling infrastructure to maximize datatransmission speeds over the existing cabling infrastructure. FIG. 1illustrates an example of an embodiment of such a mechanism. Asillustrated, network device 110 is coupled to link partner 130 vianetwork cabling 120. Network cabling 120 can represent a part of anexisting cabling infrastructure and can include a plurality of conductorpairs 124 _(n). For example, up to four copper twisted wire pairs can beincluded in an Ethernet cable.

In the example embodiment of FIG. 1, each of the conductor pairs 124_(n) is coupled to a respective physical layer device (PHY) 114 _(n) viaassociated connectors, magnetics, etc. Each PHY 114 _(n) can be designedto communicate over a single conductor pair 124 _(n) with a respectivePHY in link partner 130. In one example, PHY 114 _(n) can be based on aBroadcom BroadR-Reach® PHY, which is designed to perform all of thephysical layer functions for communication over a single copper twistedwire pair (e.g., FlexRay™) at distances up to 1000 meters.

In general, PHY 114 _(n) is a Layer 1 device that can be designed toconnect a Layer 2 data link layer device (e.g., media access control(MAC) device) to a physical medium. In an example implementation of aPHY, the PHY can include a physical coding sublayer (PCS), a physicalmedium attachment (PMA) sublayer, and a physical medium dependent (PMD)layer. In combination, the PHY can include suitable logic, circuitry,and/or code that enables transmission and reception of data with a linkpartner. In this process, the PHY can be configured to handle physicallayer requirements, which include, but are not limited to,packetization, data transfer and serialization/deserialization (SERDES).

In the present invention, network device 110 can be designed toconfigure the operation of PHYs 114 _(n) based on a discovery of thephysical cabling that connects network device 110 to link partner 130.In that regard, network device 110 can be designed to perform channeldiagnostics that examine one or more properties of the communicationchannel. Here, the identification of the one or more properties of thecommunication channel can be used to determine a data transmissioncapacity of the communication channel.

For example, network device 110 can be designed to determine a number ofconductor pairs 124 _(n) that are available between network device 110and link partner 130. In another example, network device 110 can bedesigned to determine a length of network cable 120. In yet anotherexample, network device 110 can be designed to determine a type ofcabling (e.g., Category 3, 5e, 6, 6A, 7, 7A, 8, 8A, etc. Ethernetcabling) used to connect network device 110 to link partner 130. In oneembodiment, measurements such as insertion loss and cross talk that areperformed by a cable diagnostic module can be used to determine the typeof cabling. An example of the use of a PHY to perform channeldiagnostics is included in U.S. Pat. No. 7,664,972, entitled “System andMethod for Controlling Power Delivered to a Powered Device Based onCable Characteristics,” which is incorporated herein by reference in itsentirety.

FIG. 2 illustrates an example embodiment of a PHY module thatincorporates a cable diagnostics module. As illustrated, PHY module 200includes transmit/receive (TX/RX) module 202, registers 204, cablediagnostics module 206, and controller 208. In general, TX/RX module 202facilitates a communication interface between cable diagnostics module206 and the signals carried on the communication cable. In variousembodiments, cable diagnostics module 206 can perform the cablediagnostics independently or in cooperation with an active datacommunication process that is occurring with a link partner. As would beappreciated, the specific mechanism and corresponding method by whichcable diagnostics module 206 operates in the context of a cooperativecable diagnostic would be implementation dependent.

Having described an example embodiment of a PHY module, reference is nowmade to the flowchart of FIG. 3. As would appreciated, the features ofthe present invention is not limited to the specific sequence of stepsillustrated in the flowchart. Variations in the sequence of steps can beused to accomplish the same result of configuring a network device.

As illustrated, the example process begins at step 302 where thecommunication channel characteristics are determined. The communicationcable characteristics can be determined through an identification ofvarious cabling parameters by cable diagnostics module 206, which can beconfigured to operate under the control of controller 208. In oneexample, cable diagnostics module 206 can be designed to generate andtransmit a signal (e.g., pulses) into the communication cable coupled tothe diagnostic device port, and to measure a return or reflected signalreceived by TX/RX module 202. Signals received by TX/RX module 202 arethen processed by cable diagnostics module 206 to determine variouscabling parameters reflective of communication channel characteristics.

A simple example of a cabling parameter that can be identified iswhether a communication channel is active. This can be determined bywhether PHY module 200 detects any link energy. In another example, PHYmodule 200 can determine a cable length through time-domainreflectometry (TDR), which relies on the transmission of a pulse intothe communication cable and the measurement of returned reflections ofthe transmitted pulse. The cable length or a distance to a cable faultcan be determined from the time difference between the transmitted andreflected pulse. In yet another example, PHY module 200 can performmeasurements (e.g., insertion loss, cross talk, etc.) that can be usedto determine a cabling type (e.g., Category 3, 5e, 6, 6A, 7, 7A, 8, 8A,etc. Ethernet cabling). The measurements taken by PHY module 200 can bestored in memory registers 204 or other memory element. The informationstored in memory registers 204 can then be retrieved by a host forconfiguration of the network device.

The determination of the number of available conductor pairs, the lengthof the cable, the type of cable, etc. enables a determination of thepotential modes of operation (e.g., data rate) that can be used for thetransmission of data over the cable. For example, the greater the numberof available conductor pairs the greater the communication capacity.Assuming that a single conductor pair can support a 400 Mbit/s datarate, then two available conductor pairs can be combined to support an800 Mbit/s data rate, while four available conductor pairs can becombined to support a 1.6 Gbit/s data rate. The length of the cable andthe cabling type is also relevant to the potential mode of operation.For example, a PHY can accommodate significantly longer link distanceswhen lowering the data rate, or can accommodate lower quality cablingwhen lowering the data rate.

In addition to identifying the characteristics of the communicationchannel, network device can also be designed to identify thecapabilities of the link partner at step 304. The identification of thelink partner's capabilities through an exchange of capabilityinformation would enable the network device to identify a commonoperating mode that can best leverage the identified characteristics ofthe communication channel.

In one embodiment, network device 110 and link partner 130 can exchangecapability information through an auto-negotiation process that isextended via auto-negotiation next-page messages. In one example, theauto-negotiation next-page messages can be used to exchange capabilityinformation that relates to the use of BroadR-Reach® abilities over aplurality of conductor pairs. In another embodiment, the link can bedesigned to start up with a minimum number of pairs (e.g., one pair),and once the link is up, a further capability exchange can be performedusing a protocol such as LLDP.

In one embodiment, the auto-negotiation process can be conducted for aset of conductor pairs. In another embodiment, the auto-negotiationprocess can be conducted for a single conductor pair. In thisembodiment, the auto-negotiation process for a single conductor pair canbe applied to a plurality of conductor pairs through an advertisement ofa number of available conductor pairs or an advertisement of a ratecapability per pair along with a number of available conductor pairs.

After the communication channel characteristics have been identified anda capability exchange has occurred, network device 110 and link partner130 can perform a rate selection at step 306. As would be appreciated,this rate selection process can be performed in a variety of waysdepending on the particular implementation of the configuration process.In general, the configuration process is designed to activate one ormore of the available conductor pairs to achieve a desired datatransmission rate. The desired data transmission rate can represent themaximum possible data rate or can represent the data rate that issufficient to meet the anticipated data transmission needs betweennetwork device 110 and link partner 130.

Here it should be noted that the rate selection process can also beperformed in consideration of the signaling mechanism. As would beappreciated, the signaling mechanism can be selected and negotiatedbetween network device 110 and link partner 130. In one embodiment, thesignaling mechanism is selected in consideration of the communicationchannel characteristics, network device capabilities and rate selection.For example, the signaling mechanism can identify the type of modulation(e.g., PAM-5, PAM-16, etc.), voltage levels, signal constellation, errorcorrection, etc. that are used.

After the rate selection process is completed, network device 110 canthen configure one or more PHYs 114 _(n) at step 308 for operation basedon the number of channels to be configured over respective conductorpairs 124 _(n). For example, if the configuration process determinesthat a desired data rate can be achieved using conductor pairs 124 ₁ and124 ₂, then network device 110 can configure PHYs 114 ₁ and 114 ₂ foroperation. In general, a particular set of conductor pairs can beselected to produce a desired data rate. For example, operation can bedefined for 1 Gbit/s per pair, 1 Gbit/s per two pairs, 2 Gbit/s perpair, 2.5 Gbit/s per pair, 2.5 Gbit/s per two pairs, 5 Gbit/s per pair,5 Gbit/s per two pairs, 5 Gbit/s per three pairs, etc.

In general, signaling and speed over a conductor pair would relate tothe capacity of the channel discovered. In one embodiment, signaling canbe based on signaling for a 2.5 Gbit/s channel in a 10 GBASE-T link or a250 Mbit/s channel in a 1000 BASET-T link. In various scenarios, the 2.5Gbit/s channel can be slowed down to a 0.5 Gbit/s channel, a 1 Gbit/schannel, a 1.5 Gbit/s channel, etc., or the 250 Mbit/s channel can besped up to a 500 Mbit/s channel, a 750 Mbit/s channel, a 1 Gbit/schannel, etc.

As illustrated in FIG. 1, PHYs 114 _(n) operate in association withaggregation layer 112, which is designed to aggregate data streamssupported by PHYs 114 _(n) into an aggregated data stream having theselected data rate. Aggregation layer 112 can be embodied in variousways.

As illustrated in FIG. 4A, aggregation at the physical layer (APL) canbe used. Here, APL is located below the MAC layer and allows a singleIEEE 802.3 MAC sublayer to treat a collection of underlying PHYs as asingle logical link. APL can thereby create an Ethernet link that has abandwidth that is greater than can be achieved by a physical link over asingle conductor pair. In general, APL can be designed to separateEthernet packets into fragments and to distribute the fragments across acollection of PHY interfaces. A sequence number can be used to identifyeach fragment, thereby allowing a receiving APL sublayer to reconstructthe delivered packets to the receiving MAC.

As would be appreciated, the selective activation of one or more PHYsthat have an aggregated data transmission rate that matches the MAC datatransmission rate would not yield any significant issues. Where theselective activation of one or more PHYs leads to a mismatch in theinterface between the PHY layer and the MAC layer, then a deferencemechanism in the transmission direction may need to be used such thatthe PHY can signal to the MAC to back off on further transmissions.

In another embodiment, aggregation can also be performed above the MAClayer. FIG. 4B illustrates an example of such an embodiment. In thisexample embodiment, a link aggregation (LAG) sublayer is situated abovethe MAC layer. In presenting a single MAC client interface, LAG sublayercan be designed to perform a frame distribution and collection function.As would be appreciated, the aggregation function can be implemented invarious ways within the protocol stack. In yet another embodiment, theaggregation can be performed through teaming, which performs theaggregation at Layer 3 or higher.

Regardless of the particular implementation of the aggregationmechanism, the aggregation enables a configuration ofselectively-activated PHYs that are targeted to identified communicationchannel characteristics. Support of multi-conductor pair operating modesthat can produce greater than gigabit/s data transmission rates overexisting cable infrastructures is thereby enabled.

As noted, one of the constraints in adopting next-generation datatransmission rates is the increased energy costs. In one embodiment, anenergy efficiency control policy can be used to minimize a transmissionperformance impact while maximizing energy savings. In one embodiment,energy efficiency control policies can base their energy-savingdecisions on a combination of settings established by an IT manager andthe properties of the traffic on the link itself.

FIG. 5 illustrates an example embodiment of an energy efficiency controlpolicy in a network device. In various embodiments, network device 510can represent a switch, router, endpoint (e.g., server, client, VOIPphone, wireless access point, surveillance camera, etc.), or the like.As illustrated, network device 510 includes PHY 512, MAC 514, and host516. As FIG. 5 further illustrates, network device 510 also includesenergy efficiency control policy entity 518. In general, energyefficiency control policy entity 518 can be designed to determine whento enter an energy saving state, what energy saving state (i.e., levelof energy savings) to enter, how long to remain in that energy savingstate, what energy saving state to transition to out of the previousenergy saving state, etc.

In general, energy efficiency control policy entity 518 can comprisesuitable logic, circuitry, and/or code that may be enabled to establishand/or implement an energy efficiency control policy for the networkdevice. In various embodiments, energy efficiency control policy entity518 can be a logical and/or functional block which may, for example, beimplemented in one or more layers, including portions of the PHY orenhanced PHY, MAC, switch, controller, or other subsystems in the host,thereby enabling energy-efficiency control at one or more layers.

In one example, energy efficient Ethernet such as that defined by IEEE802.3az can provide substantial energy savings through the use of a lowpower idle mode and/or subrating. In general, the low power idle modecan be entered when a transmitter enters a period of silence when thereis no data to be sent. Power is thereby saved when the link is off.Refresh signals can be sent periodically to enable wake up from thesleep mode. Subrating can be used to reduce the link rate to a sub-rateof the main rate, thereby enabling a reduction in power. In one example,this sub-rate can be a zero rate, which produces maximum power savings.In various embodiments, energy efficiency control policy 518 can bedesigned to apply energy saving techniques to a particular conductorpair or to a plurality of conductor pairs. For example, energyefficiency control policy 518 can apply subrating to the plurality ofconductor pairs by powering off one or more of the activatedcommunication channels.

As would be appreciated, the principles of the present invention can beapplied symmetrically or asymmetrically to a link. In one embodiment,power over Ethernet techniques can also be applied to deliver power froma power sourcing equipment to a powered device over one or more of theconductor pairs. In general, the principles of the present invention canbe applied to speeds higher than 10 G, such as 40 G, 100 G, 400 G andbeyond.

Another embodiment of the invention may provide a machine and/orcomputer readable storage and/or medium, having stored thereon, amachine code and/or a computer program having at least one code sectionexecutable by a machine and/or a computer, thereby causing the machineand/or computer to perform the steps as described herein.

These and other aspects of the present invention will become apparent tothose skilled in the art by a review of the preceding detaileddescription. Although a number of salient features of the presentinvention have been described above, the invention is capable of otherembodiments and of being practiced and carried out in various ways thatwould be apparent to one of ordinary skill in the art after reading thedisclosed invention, therefore the above description should not beconsidered to be exclusive of these other embodiments. Also, it is to beunderstood that the phraseology and terminology employed herein are forthe purposes of description and should not be regarded as limiting.

1-20. (canceled)
 21. A method, comprising: identifying characteristicsof a communication channel in a network link; receiving informationregarding capabilities of devices associated with the network link;selecting a data transmission rate; determining an aggregation ofcommunication links that combined have a capacity to provide data at thedata transmission rate; and providing a communication over theaggregation of communication links in the network link.
 22. The methodof claim 21, wherein the characteristics of the communication channelinclude a number of conductor pairs in the network link, a length of anetwork cable in the network link, or a type of cable in the networklink, or a combination thereof.
 23. The method of claim 21, whereinreceiving information regarding the capabilities of the devicesassociated with the network link includes performing a capabilityexchange between network partners.
 24. The method of claim 21, whereinthe data transmission rate is selected based on the identifiedcommunication channel characteristics.
 25. The method of claim 21,wherein the data transmission rate is selected based on the receivedcapabilities of the devices associated with the network link.
 26. Themethod of claim 21, wherein the network link includes a plurality ofconductor pairs, and at least one of the communications links is basedon a separate physical layer device that interfaces with one of theplurality of conductor pairs.
 27. The method of claim 21, whereinproviding a communication over the aggregation of communication links inthe network link includes activating a set of the communication links inthe aggregation of communication links for providing the communication.28. The method of claim 21, wherein determining the aggregation ofcommunication links occurs below a media access layer.
 29. The method ofclaim 21, wherein determining the aggregation of communication linksoccurs above a media access layer.
 30. A system, comprising: at leasttwo physical interfaces coupled to a network link, wherein the at leasttwo physical interfaces individually include a physical layer deviceconfigured for electrical communication over a conductor pair in thenetwork link; a computing machine configured to execute instructions,the instructions directing the computing machine to implement anaggregation layer, wherein the aggregation layer is implemented to:identify types of the conductor pairs in the network link; receivecapabilities of devices coupled to the network link; determine atransmission rate; select a set of physical interfaces of the at leasttwo physical interfaces; and provide a communication to the network linkthrough the set of physical interfaces at the transmission rate.
 31. Thesystem of claim 30, wherein the selection of the set of physicalinterfaces is based on the identified types of the conductor pairs inthe network link.
 32. The system of claim 30, wherein the selection ofthe set of physical interfaces is based on the received capabilities ofthe devices coupled to the network link.
 33. The system of claim 30,wherein the set of physical interfaces is selected such that anaggregation of the physical interfaces allows for the communication tothe network link through the set of physical interfaces to be at thetransmission rate.
 34. The system of claim 30, further comprising acable diagnostics module, wherein the aggregation layer is furtherimplemented to receive information from the cable diagnostics module,and wherein the identification of the types of the conductor pairs isbased on the information received from the cable diagnostics module. 35.A method, comprising: determining a type of a plurality of conductorpairs that are used in a network link that couples a network device to alink partner; selecting, based on the determined type of the pluralityof conductor pairs, a data transmission rate for use by the networkdevice over the network link; and configuring the network device tocommunicate at the data transmission rate through an aggregation of aplurality of communication links, wherein the plurality of communicationlinks are based on respective separate physical layer devices thatinterface with respective ones of the plurality of conductor pairs. 36.The method of claim 35, wherein configuring the network device tocommunicate at the data transmission rate through the aggregation of theplurality of communication links occurs below a media access layer. 37.The method of claim 35, wherein configuring the network device tocommunicate at the data transmission rate through the aggregation of theplurality of communication links occurs above a media access layer. 38.The method of claim 35, further comprising, prior to determining thetype of the plurality of conductor pairs, selecting a first number ofcommunication links and providing a communication over the first numberof communication links; and, subsequent to selecting a data transmissionrate, selecting a second number of communication links for theaggregation of the plurality of communication links.
 39. The method ofclaim 38, wherein the second number is greater than the first number.40. The method of claim 38, wherein the communication links in thesecond number of communication links are different that thecommunication links in the first number of communication links.